I bought a bag of potatoes and a hand of bananas on Sunday (from Costco) and just let them sit in the kitchen until Friday, when I noticed water oozing out of a few of the bananas.
Then, the next day, I found that a few thumb-sized spots on the potatoes had also become mushy and had a terrible smell. This ooze is pure white, feeling and looking like mashed potatoes (but I never cooked them), not the normal darkening I am used to in potato rot.
It's like something just spoiled these two produce products and cut short the full aging/ripening process after one week.
So, I focused on the potatoes, since they had the strangest spoilage, and went online to understand this. I could only find one match, which is also very recent (written just 1 month ago, but I believe the experience was 10 months ago) and even has a video of this mush.
That match suspects either "freezing injury" or "rot bacteria". I wonder if this bacteria is known to spread to bananas. Additionally, I wonder if "water droplets" left on the potato could simply dissolve the potato if stored a little on the warm side. Maybe the potatoes were somehow stored over the last few months or even the entire winter...maybe this year's hot summer is special...I'm sure that there are many other possible explanations here.
So, what is the most likely explanation?
The bananas were a ripe yellow even from purchase, and did get some brown spots of ripening, but never seemed to go through the full blackening spoiling process I am used to. The banana fruit itself behind the peel had not darkened like normal over-ripened bananas. It was standard "ripe yellow", just somehow decomposing to liquid/mush throughout the bottom half of the banana. The peels had some brown spots like normal ripening, but never developed black spots (black spots are my usual indicator that I need to eat them within a few days or the interior will start to get mushy, but these particular bananas never had this indicator).
I did not see any eyes/sprouts grow from the potatoes like I normally do (and they had no green on them, these are huge perfectly-tan russet potatoes).
For both, the unspoiled parts tasted good.
As for the kitchen temperature, it has been a bit hot (maybe as high as 80F inside) for the first few days and normal (about 72F) for the last few days. As for the kitchen humidity, it has been normal always (about 55%). The purchase and storage was in Minnesota.
If this ever happens again, I will make a video of the spoiling mush to help explain this better.